<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div {
      width: 300px;
      height: 300px;
      background-color: pink;
    }
  </style>
</head>

<body>

  <div></div>

  <script>

    const div = document.querySelector('div')
    div.addEventListener('mouseenter', function () {
      console.log('我经过来')
    })
    div.addEventListener('mouseleave', function () {
      console.log('我离开了')
    })

  </script>

</body>

</html>